1. Field of the Invention
This invention relates to a pressure-sensitive recording medium to be used for a pressure-sensitive recording device such as typewriter, etc. More particularly, the present invention relates to a novel pressure-sensitive recording medium which has been deviced to exhibit good transfer performance event at small impact pressure or impact energy during recording.
2. Related Background Art
There have been heretofore been widely used typewriters which perform printing by utilizing impact pressure by means of a type bar or a print ball, and also various pressure-sensitive recording media such as correctable ink ribbon, etc. have been also known. However, in recent years, there is an increasing demand for making the noise during printing operation lower, and typewriters utilizing a daisy wheel in place of the type bar or print ball as mentioned above are becoming to be employed widely. The typewriter utilizing a daisy wheel, in place of employing the printing method of printing letters by strong impact pressure as in the case of the typewriter utilizing the type bar or the print ball, utilizers an impact system in which the printing letters are lightly pushed as suitable for effecting lower noise, but even such system cannot be said to satisfy fully the requirements for lowered noise yet. Thus, efforts have been made to further lower impact pressure or impact energy.
Whereas, the pressure-sensitive recording medium as proposed in U.S. Pat. No. 3,825,437 such as the above correctable ink ribbon, etc. is generally constituted by use of a film substrate and having an ink layer composed mainly of a film forming resin, namely a high molecular weight resin having generally a weight average molecular weight of 20,000 or more and an oil substantially non-compatible with said resin. In such a pressure-sensitive transfer recording medium, when printing is performed at weak impact pressure or low impact energy, poor transfer such as letter defect, etc. has occurred frequently thereby making it difficult to obtain satisfactory sharp printed images. Also, when printing is performed at such weak impact pressure or low impact energy, the printed image on a material to be attached such as paper is under the state where printed images are weakly attached on the surface of the material to be attached, whereby there ensue such problems as the printed images being readily peeled off when a force such as friction or bending is applied.